ck, what type of printer do you have? I use to do that on quilts I didn't wash and someone told me they would wash out. I tried it sure enough even washing the fabric the colors would go immediately and the black faded a lot. I have tried HP photo and Epson, which is the same type of ink the photo companies use. Epson even washes out, even with heat setting, prewashing.
I talked to Epson, they said they have not come up with a ink that is color fast for fabric yet.